Two-stage pump with internal washing system



May 11, 1965 H. N. BLAKESLEE 3,182,599

TWO-STAGE PUMP WITH INTERNAL WASHING SYSTEM Filed May 27, 1963 2Sheets-Sheet 1 Cemmfn Flan 62 m livl I ff; l2 11g 7 /ILV IIL '70 Salaam*n JNVENTOR MMA y /vELsaA/zAA/fszff B Q//mz/ ffm( y @aga WM 956eme/n* 0m*AT ToRN EYs May 11, 1965 H. N. BLAKESLEE 3,82,599

TWO-STAGE PUMP WITH INTERNAL WASHING SYSTEM Filed May 2'7, 1963 2Sheets-Sheet 2 FIG. 2 64 99 68 j 74 FIG. 3

66 64 t 3i V V"l 164' \74 68\ y 9,94 50 Bni- 49 @9 42 y? W l INVENTUR.#Amy Nasa/v mA/aff BY Jawa@ VQ/ @ff/4Q ATTORNEYS United States PatentOilce 3,182,599 TWG-STAGE PUMP WITH INTERNAL WASHING SYSTEM Harry NelsonBlakeslee, Barrington, Ill., assigner to American Can Company, New York,N.Y., a corporation of New Jersey Filed May 27, 1963, Ser. No. 283,391Claims. (Cl. 103w50) This invention relates to a pump for a viscousmaterial and more particularly it relates to a two-stage pump havingcapabilities of effectively transferring adhesive cement products whichhave a tendency to solidify within the pump thereby rendering themovable parts immovable and thus inoperative.

In fastening plastic fittings to various hardware items by means ofepoxy cements, it is often necessary to apply small quantities of thecement into deep slots. Hypodermic needles have proved tobe particularlysuited for introducing such small deep slots, but due to the minuteorifice of the needle and the extreme viscosity of the cement, it wasfound that it was necessary to exert an extremely high pressure to forcethe cement through the orifice. This can be most easily accomplished byutilizing a pump employing the design of the present invention wherein adifferential piston arrangement is provided, and in which line airpressure is applied to the large piston portion which in turn appliespressure to a smaller piston portion which exerts pressure directly uponthe adhesive material. By using such a construction, the presentinvention provides a means whereby nominal line pressure can bemagnified many times, depending upon the ratio of the cross-sectionalareas of the large and small pistons.

The problem with further complicated by the fact that the cements tendto work their way up the cylinder walls while the pump is operating, andthey gradually harden in place, thus freezing the pistons in place andrendering the pump inoperative. Solvents can be used to wash awayunhardened cement which tends to work itself between the pistons and thecylinder walls, but such solvents cannot be allowed to combine with thecement being pumped lest it become diluted.

An object of this invention therefore is to overcome the above-mentionedproblems associated with pumps for viscous adhesive products.

Another object of this invention is to provide a novel pump constructionhaving means for internal distribution of a solvent which prevents thematerial being pumped from solidifying Within the pump and rendering themovable parts thereof inoperative.

A further object of the present invention is to provide a pumpconstruction which allows internal lubrication by a solvent whilepreventing such a solvent from intermixing with and thus diluting thematerial being pumped.

Still another object of the present invention is to provide a pump whichcan be operated by nominal line pressure but which will discharge thematerial being pumped at substantially higher pressures.

A yet further object of this invention is to provide a two-stage pumpwhich applies two separate forces to the material Ibeing pumped to thusdischarge the same at increased pressures. Y

Numerous other objects and advantages of the invention will be apparentas it is better understood from the following description, which, takenin connection with the accompanying drawings, discloses a preferredembodiment thereof.

The above objects are' achieved by providing a device havinga centraltube communicating between an inlet quantities of cement into suchpumping such adhesive cements is f' 3,182,599 Patented May 11, 1965 andan outlet and a differential piston concentrically surrounding the tube.The differential piston includes an enlarged central disc having a stemportion extending away from each of its faces. Thus, when nominal linepressure is applied to the central disc, the stem portions magnify thatpressure and apply it to the adhesive material or cement to pump thesame. The cement enters the device through a check valve at the upperend 0f the central tube and accumulates in an upper annular cavity whichsurrounds the central tube when the piston is in the down or pumpposition. When the piston retracts to an up position, it applies apressure which forces the cement from the upper annular cavity, throughthe central tube, past a lower check valve, and into a lower annularcavity. When the piston again moves to a down or pump position, itapplies a second pressure which forces the cement from the lower annularcavity and out through a minute discharge orifice. Passages are providedfor circulating a solvent between the piston and the central tube towash away the cement which might harden and prevent piston movement. Thesolvent, however, is internally distributed in such a manner that it isprevented from diluting the main body of cement which is being pumped bythe device.

Referring to the drawings:

FIG. l is a transverse sectional view embodiment of a pump invention;

p FIG. 2 is a fragmentary sectional view of the discharge end of thepump with the piston in a pump position; and

FIG. 3 is a fragmentary sectional view similar to FIG. 2 but with thepiston in a retracted position.

As a preferred or exemplary embodiment of .the invention, FiG. lillustrates a pump generally designated 10 and comprising a hollowcasing member 12 and a pair of end members 14 and 16 having stemportions 18 and 24B, respectively, extending Within said casing member.The stem 18 has internal threads 24 upper or inlet end.

of a preferred in accordance with the present on the interior of thecasing 12 at its In a like manner, the stem 20 has external threads 26which mate with internal threads 2,8 on the interior of the lower oroutlet end of the casing 12. A lock nut 3@ is vthreaded onto the stem 18and is interposed between the end member 14 and the inlet end of thecasing 12, thus regulating the distance which the stem 18 extends intothe ing the length of the stroke of the pump piston, in a manner whichwill be presently described.

A differential piston generally designated 32 is mounted within thecasing 12 and is comprised of an enlarged central disc portion 3.4i anda pair of stem portions 36 and 3S, preferably extending normally fromthe faces of the disc 34. The stem 36 extends toward the inlet end ofthe pump and partially Vinto a Vbore 40 which extends completely throughthe end member `14. The stem 38 extends toward the outlet end of thepump and into a bore 42 which extends partially through the end member16. An annular O-ring, or other suitable sealing means d4, seals theinterface between the edge of the disc 34 and the interior walls of thecasing 12. `In a like manner, an annular O-ring 46 seals the interfacebetween the stem 35 and the bore (if) and annular O-rings 48 and `StirVseal the interface between the stem 38 and the bore 42.

A raised shoulder 52 exten-ds inward beyond the end of the end memberstem portion 2t? to provide a seat for one face of the centr-al disc 34of the piston. The other face of the disc 34 seats against the bottomend of the end member stem portion 18. Thus, the effective distancebetween the innermost ends of the stem 18 and the shoulder 52 determinesthe stroke of the piston 32. Since the distance the stem portion 13extends into the casing 12 external threads 22 which mate With.

casing and thus also determin-l can be threadably adjusted by means ofthe lock nut 3f), the stroke can be varied accordingly.

The bore 40 is provided with threads 53 at its upper end to accommodatea plug 54 having a stem 56 with threads 58 which mate with the borethreads 53 to mount the plug. A bore 60, partially threaded at 62,extends through the plug 54. Within the bore 60, one end of an elongatedcentral tube 64 is suitably attached, as by shrink fitting or the like.A central bore 66 extends axially through the -tube 64. The tube itselfprojects into and through an axial bore 68 extending through the piston32. An annular O-ring 70 surrounds the lower end of the tube 64 to sealthe interface between the lower end of the tube and the piston bore 68.Additionally, an annular O-ring 72 mounted within the upper end of thepiston bore 68 serves to seal the interface between the central tube 64and the upper end of the piston 32.

An inlet fitting 74 having an internal bore '76 is mounted at the upperor inlet end of the pump and is adapted to be suitably connected to asource of adhesive or cementitious material which is to be introducedinto the pump. The fitting 74 includes a threaded stem 78 which screwsinto the threaded bore 62 of the plug 54. An inlet check valve ismounted between the lower end of the stem 7S and the upper end of thecentral tube 64, and while the check valve can be of any suitableconventional construction, it is illustrated as a spherical ball element80 and a coil compression spring S2. The ball seats against a valve seat84 formed in the lower end of the stem 78.

An outlet check valve assembly is provided at the lower end of thecentral tube 64, and is mounted at the base of the end member bore 42.The outlet check valve is comprised of a spherical ball element 86, acoil compression spring S8, and a sleeve or collar 90 having a pluralityof apertures 92 therein. The collar 90 confines the ball and spring to alinear movement without limiting the fluid flow of the material. Theball 86 seats against a valve seat 94 formed in the lower end of thecentral tube 64.

A slender discharge passage 96 communicates with the bore 42 frombeneath the outlet check valve. The end member 16 can be provided with alower threaded stem portion 98 to which can be mounted a suitable fiowdirecting assembly such as the hypodermic needle previously mentioned.

The casing 12 is provided with a pair of apertures 100 and 102 onopposite sides of the piston central disc 34. Line pressure, such as airpressure or the like, is introduced through a selector valve 104 to oneor the other of the casing apertures to thus move the piston either toan up or retract position or to a down or pump position. It can be seenthat when air is introduced through the aperture 100 and the piston 32moves to a down position, an upper annular cavity 106 is formed withinthe upper end member bore 40 between the upper end of the piston stem 36and the lower end of the end member stem 56. When air is introducedthrough the aperture 102 to move the piston 32 to an up position, theupper cavity 106 is filled by the piston and a lower annular cavity 108(FIG. 3) is formed within the lower end member bore 42 beneath the endof the piston stem 38. The line pressure thus serves as a piston drivingmeans.

In operation, cementitious material is introduced into the pump throughthe inlet fitting 74, and it flows past the upper check valve and fillsthe bore 66 of the central tube 64. When the piston is in the downposition, as shown in FIG. 1, this incoming material will also flow intoand fill the upper annular cavity 106 by virtue of the provision of atleast one, but preferably a plurality of slots or openings 110 in theportion of the central tube 64 which` is surrounded by the cavity 106.When line pressure is introduced through the easing aperture 102 andapplied to lower face of the enlarged piston disc 34, the piston raisesand the end of the upper piston stern 36, by virtue of its small area incomparison to the area of the central disc 34, applies a magnifiedpressure to the cement within the upper cavity 106, thus forcing thiscement back through the openings 110 and through the bore 66 of thecentral tube 64.

At this point, the piston will have moved to the position illustrated inFIG. 3, and a lower annular cavity 10S will have been created. Due tothe increased pressure resulting from the expulsion of the cement fromthe upper cavity 166, the lower check valve will open as shown, andcement will fill the sleeve and will flow through the apertures 92therein to fill the lower cavity 108. Because of the narrowness of thedischarge passage 96, and the high viscosity of the cement material,very little, if any, of the cement will flow through the dischargepassage 96. However, when line pressure is introduced through the casingaperture to move the piston 32 to `a down or pump position, the lowerpiston stem 33 will exert a high pressure on the cement within thecavity 168 to cause that cement, as well as some of the cement withinthe interior of the sleeve 90, to be discharged through the passage 96at extremely high pressure.

When the line pressure is again introduced through the casing aperture102, the piston 32 raises again and the foregoing cycle is repeated. Itcan thus be seen that the pump of the present invention actually has twoseparate pressure stages, the first of which is applied to cement in theupper cavity to fill the lower cavity, and the second of which isapplied to cement in the lower cavity to discharge the same.

The constant reciprocating movement of the piston 32 tends to cause asmall amount of the cement being pumped to work its way between theoutside of the central tube 64 and the piston bore 68. If this cementwere allowed to remain trapped therein, it would harden-with somecernents quite rapidly-and prevent the piston from moving, thusrendering the pump inoperative. To prevent this from occurring, asolvent distribution system is provided. The system includes an inletpassage 112 in the end member 16 which supplies solvent to an enlargedport 114 in communication with the end member bore 42. An inlet port 116in the piston stem 38 is juxtaposed to the enlarged port 114 forpermitting the solvent to be introduced into the interior of the piston32. An outlet port 113 is provided on the piston stem 36 for exhaustingthe solvent from the piston 32. Between the ports 116 and 118, thepiston bore 68 is enlarged slightly to provide a narrow annular cavity120 in which the solvent can circulate to wash the exterior of thecentral tube 64 and the interior of the piston 32. The spent solventpasses out the outlet port 118 into an enlarged port 122 and from therethrough an outlet passage 124 in the end member 14. The enlarged ports114 and 122 ensure that solvent will continually flow to the cavity 120regardless of whether the piston 32 is in the up position, the downposition, or any position therebetween. The solvent itself is suppliedto the pump from a reservoir (not shown) by any suitable means such as aconventional positive displacement pump. The spent solvent can befiltered or otherwise purified, if desired, to permit it to be returnedto the reservoir to be recirculated.

As was aforementioned, it is important that the solvent be preventedfrom mixing with the cement being pumped and thus diluting the same.Such mixing is prevented by the use of sealing rings adjacent each endof the annular cavity 126. The sealing ring 70 on the lower end of thecentral tube 64 is located just below the inlet port 116 to provide aneffective seal between the central tube 64 and the piston bore 68 andthus prevent downward solvent leakage. Similarly, the sealing ring 72 inthe upper end' of the piston stern 36 is located just above the outletport 118 to prevent upward solvent leakage. It is thus seen that thesolvent liow is confined to the annular cavity 120 and the solvent isthus prevented from contacting the cement being pumped.

The material contemplated for use with the pump of the present inventionhas been alternately referred to as a cement or an adhesive and, whileother high viscosity materials could be pumped by the device describedherein, the preferred materials are those high viscosity twocomponent,`short pot-life reactive organic adhesives which generally comprise amixture o-f an epoxy resin and an amine or amide resin. An example ofsuch an adhesive is that described in United States Patent No.2,986,539, issued to L. E. Schniepp et al. A solvent suitable for usewith an epoxy two-component adhesive is methyl ethyl ketone.

It is thought that the invention and many of its attendant features willbe understood from the foregoing description, and it will be apparentthat various changes may be made in the form, construction andarrangement of parts without departing from the spirit and scope of theinvention or sacrificing all of its material advantages, the formhereinbefore described being merely a preferred embodiment thereof.

I claim:

1. A two-stage pump for viscous material comprising a casing; an endmember assembly mounted at each end of said casing and having anaperture therein, one of said apertures deiining an inlet and the otherof said apertures dening an outlet; valve means at said inlet andoutlet; a central tube extending between said end member assemblies andhaving an axial bore which directs the flow of material between saidinlet and said outlet; a piston concentrically surrounding said centraltube; said piston being movable to a pump position in which it is at theend of its stroke in the outlet direction, and also being movable to aretracted position in which it is at the end of its stroke in the inletdirection; a first cavity being formed between said inlet end memberassembly and said piston when said piston is in its pump position; saidcentral tube having lateral passage means therein in the region of saidIirst cavity to permit iiow between said axial bore and said firstcavity; a second cavity being formed below the outlet end of saidcentral tube between said outlet end member assembly and said pistonwhen said piston is in its retracted position; and means for selectivelymoving said piston to a pump position whereat material from said inletwill I'ill said iirst cavity and simultaneously material from saidsecond cavity will be discharged under pressure through said outlet;said means also selectively operable for moving said piston to aretracted position whereat material from said lirst cavity will beforced under pressure into said central tube axial boreandsimultaneously material from said central tube axial bore will beforced under pressure into said second cavity.

2. A pump as delined in cla-im 1 wherein said valve means includes aball check valve located at each end of said central tube.

3. A pump as defined in claim 1 wherein said end member assemblies areadjustable axially of said pump to vary the stroke of said piston.

4. A pump as delined in claim 1 wherein said piston is a dilferentialpiston having an enlarged central disc which receives the pressure fromsaid selective moving means and transmits it to the smaller pistonportions which extend into said cavities.

5. A pump as deiined in claim 1 but further characterized by an annularpassage between the interior of said piston and the exterior of saidcentral tube and means for circulating solvent through said annularpassage while preventing such solvent from intermixing with and dilutingthe material being pumped.

6. Apparatus for pumping a viscous adhesive material comprising: -ahollow casing having an inlet end and an outlet end; valve meansadjacent said inlet and outlet ends; an inlet end member mounted at theinlet end of the casing, having an aperture extending therethroughadapted to communicate with a source of material to be pumped, andhaving a stem portion extending into said casing; an outlet end membermounted at the outlet end of the casing, having an aperture extendingpartially therethrough and terminating into a discharge passage, andhaving a stem portion extending into said casing; a differential pistonwithin said casing having an enlarged central disc reciprocable betweenthe innermost ends of said stem portions and having a pair of reducedportions extending into the apertures in said end members; said pistonalso having a central bore extending axially therethrough; meansmounting a central tube within said inlet end member aperture; saidcentral tube extending substantially through said piston central bore,having at least one lateral opening therein adjacent to said mountingmeans to provide for communication between :said inlet end memberaperture and the interior of said central tube, and terminating short ofthe terminus of said outlet end member aperture; a iirst cavity beingformed between one of said piston reduced portions and said central tubemounting means when said piston central disc contacts said outlet endmember; a second cavity being formed between the other of said pistonreduced portions and the terminus of said outlet end member aperturewhen said piston central disc contacts said inlet end member; selectivepiston drive means `operable to move the one piston reduced portion intosaid first cavity to force the adhesive material therein through saidcentral tube lateral opening and into the interior of said central tubewhile simultaneously forcing some adhesive material out of the intubelateral opening; and a solvent distribution system for continuouslypassing solvent between the exterior of `said central tube and theinterior of said piston to prevent any of the adhesive material fromhardening therein; said solvent distribution system including means -toprevent any of said solvent from intermixing with and diluting theadhesive material being pumped.

7. Apparatus as defined in claim 6 wherein said solvent distributionsystem comprises a passageway in each of said end members for providingand removing said solvent, a passageway in each of said piston reducedportions communicating with said end member passageways, and an enlargedportion of sald piston central bore between said piston passageways tothus provide an annular cavity surrounding said central tube in whichthe solvent can continually wash the exterior of said central tube andthe interior of said piston.

8. Apparatus as defined in claim 7 wherein the means for preventing thesolvent from intermixing with and diluting the adhesive material beingpumped comprises sealing means between said central tube and said pistonbore at each end of said annular cavity.

9. Apparatus as dened in claim 6 wherein said valve means includes aninlet ball check valve at the inlet end of said central tube and anoutlet ball check valve at the outlet end of said central tube.

10. Apparatus as defined in claim 6 wherein at least one of said endmembers is axially adjustable to permit the stroke of said piston to bevaried.

References Cited by the Examiner UNITED STATES PATENTS LAURENCE V.EFNER, Primary Examiner. ROBERT M. WALKER, Examiner.

1. A TWO-STAGE PUMP FOR VISCOUS MATERIAL COMPRISING A CASING; AN ENDMEMBER ASSEMBLY MOUNTED AT EACH END OF SAID CASING AND HAVING ANAPERTURE THEREIN, ONE OF SAID APERTURE DEFINING AN INLET AND THE OTHEROF SAID APERTURES DEFINING AN OUTLET; VALVE MEANS AT SAID INLET ANDOUTLET; A CENTRAL TUBE EXTENDING BETWEEN SAID END MEMBER ASSEMBLIES ANDHAVING AN AXIAL BORE WHICH DIRECTS THE FLOW OF MATERIAL BETWEEN SAIDINLET AND SAID OUTLET; A PISTON CONCENTRICALLY SURROUNDING SAID CENTRALTUBE; SAID PISTON BEING MOVABLE TO A PUMP POSITION IN WHICH IT IS AT THEEND OF ITS STROKE IN THE OUTLET DIRECTION, AND ALSO BEING MOVAABLE TO ARETRACTED POSITION IN WHICH IT IS THE END OF ITS STROKE IN THE INLETDIRECTION; A FIRST CAVITY BEING FORMED BETWEEN SAID INELT END MEMBERASSEMBLY AND SAID PISTON WHEN SAID PISTON IS IN ITS PUMP POSITION; SAIDCENTRAL TUBE HAVING LATERAL PASSAGE MEANS THEREIN IN THE REGION OF SAIDFIRST CAVITY TO PERMIT FLOW BETWEEN SAID AXIAL BORE AND SAID FIRSTCAVITY; A SECOND CAVITY BEING FORMED BELOW THE OUTLET END OF SAIDCENTRAL TUBE BETWEEN SAID OUTLET AND MEMBER ASSEMBLY AND SAID PISTONWHEN SAID PISTON IS IN ITS RETRACTED POSITION; AND MEANS FOR SELECTIVELYMOVING SAID PISTON TO A PUMP POSITION WHEREAT MATERIAL FROM SAID INLETWILL FILL SAID FIRST CAVITY AND SIMULTANEOUSLY MATERIAL FROM SAID SECONDCAVITY WILL BE DISCHARGED UNDER PRESSURE THROUGH SAID OUTLET; SAID MEANSALSO SELECTIVELY OPERABLE FOR MOVING SAID PISTON TO A RETRACTED POSITIONWHEREAT MATERIAL FROM SAID FIRST CAVITY WILL BE FORCED UNDER PRESSUREINTO SAID CENTRAL TUBE AXIAL BORE AND SIMULTANEOUSLY MATERIAL FROM SAIDCENTRAL TUBE AXIALLY BORE WILL BE FORCED UNDER PRESSURE INTO SAID SECONDCAVITY.